Methods and systems for the management of sequence-sensitive, connection-oriented traffic on a multi-link aggregated port

ABSTRACT

The present invention provides methods and systems for the management of sequence-sensitive, connection-oriented traffic on a multi-link aggregated port. The methods include: at a first end of a multi-link aggregated port, selectively enabling a first constituent link of a plurality of constituent links to transmit data traffic in a first direction via a transmit state block associated with the first constituent link; and, at the first end of the multi-link aggregated port, selectively enabling the plurality of constituent links to receive data traffic from a second direction via a plurality of receive state blocks associated with the plurality of constituent links. The methods also include: at a second end of the multi-link aggregated port, selectively enabling a second constituent link of the plurality of constituent links to transmit data traffic in the second direction via a transmit state block associated with the second constituent link; and, at the second end of the multi-link aggregated port, selectively enabling the plurality of constituent links to receive data traffic from the first direction via a plurality of receive state blocks associated with the plurality of constituent links.

FIELD OF THE INVENTION

The present invention relates generally to the telecommunications andnetworking fields. More specifically, the present invention relates tomethods and systems for the management of sequence-sensitive,connection-oriented traffic on a multi-link aggregated port, such as anInstitute of Electrical and Electronics Engineers (IEEE) 802.3ad LinkAggregation Group (LAG) or the like.

BACKGROUND OF THE INVENTION

Link aggregation is a data networking term that refers to using aplurality of Ethernet network cables/ports in parallel in order toincrease link speed beyond the capability of any single cable/port.Alternative terms for link aggregation include Ethernet trunking,Network Interface Card (NIC) teaming, port trunking, port teaming, andNIC bonding. LAGs are based on the IEEE 802.3ad standard. The variousIEEE 802.3 standards are incorporated by reference herein.

LAGs provide a relatively inexpensive mechanism by which a high-speedbackbone network is set up, the network transferring more data than asingle port or device is capable of utilizing. This allows a pluralityof devices to communicate simultaneously at their full single-portspeed, while prohibiting any single device from monopolizing allavailable backbone capacity. Additionally, LAGs allow the backbonenetwork to incrementally grow as network demand increases, withouthaving to replace equipment.

LAGs allow for the grouping of a plurality of logical or physical linksinto a single logical link, thereby providing improved bandwidthflexibility and resource allocation. The IEEE 802.3ad standard allowsfor the aggregation of multiple Ethernet ports, such as 1 Gbps or 10Gbps Ethernet ports, up to a maximum aggregated 80 Gbps bandwidth. Forexample, a plurality of GigE interfaces may be bundled together topresent a single logical interface that controls the resources of all ofthe constituent links (e.g. two GigE interfaces may be bundled togetherto present a single 2 Gbps logical interface that controls the resourcesof the two GigE interfaces). Fiber optic backbones typically operate at10 Gbps line rates. 10 GigE networking interfaces exist, the they arerelatively expensive and are typically used for specialized tasks. LAGsare useful for grouping single GigE networking interfaces fortransmission on a 10 Gbps backbone.

Typically, LAGs have been used in connectionless, best-effortenvironments in which there is no standard relationship between onepacket or frame and the next packet or frame (e.g. there is no orderingrelationship between one packet or frame and the next packet or frame),nor is there any need to reserve resources for said data. For example,in standard Ethernet environments, there is no data ordering guaranteefrom one frame to the next frame, nor is there any data deliveryguarantee. It is assumed that higher layers have the ability to handleboth the reordering of data into an ordered stream and packet or frameloss. This is not an issue in a traditional data network as there is noframe ordering requirement. For example, a computer operating a browserthat is capable of viewing hyper-text markup language (HTML) documentsreassembles frames in the correct order. A user may experience a delayassociated with this process, but it is not critical as this is viewedas a best-effort environment.

In general, attempts are made to preserve data ordering via sub-flowidentification. Data associated with a given sub-flow is transmittedacross the same constituent link in order to guarantee data ordering.Data is received in order because it is transmitted on the sameconstituent link and each frame is received in the order it wastransmitted. However, there is no standard mechanism for identifyingsub-flows, with sub-flow identification left to individualimplementations.

IEEE 802.3ad defines a Marker protocol to guarantee data ordering. ThisMarker protocol involves a sending side notifying a receiving side thatit is about to move a sub-flow from one link to another. However, itdoes not specify flow identification or resource reservation for a givenflow. Resource reservation allows physical resources to be reserved inorder to provide connection-oriented functions, such as rate enforcementand quality of service guarantees.

With the advent of sequence-sensitive, connection-oriented traffic, suchas Pseudowire Emulation Edge-to-Edge (PWE3) traffic, and its deliveryacross LAGs, data ordering and delivery guarantees become much moreimportant, as these are properties of layer 2 connection-orientedservices. PWE3 is an emulation over Ethernet of native services, such asAsynchronous Transfer Mode (ATM), Frame Relay (FR), Time DivisionMultiplexed (TDM), and Synchronous Optical Network/Synchronous DigitalHierarchy (SONET/SDH) services. Due to the characteristics of theseservices, out-of-order packets or frames are not tolerated by higherlayers and call admission control during call setup is used to reserveresources in order to guarantee quality of service parameters.

Thus, what is needed is an improved mechanism by whichsequence-sensitive, connection-oriented data is allocated resources,delivered, and received across LAGs.

BRIEF SUMMARY OF THE INVENTION

The present invention provides an improved mechanism for allocatingresources and preserving the sequence of connection-oriented traffictraversing a LAG. The present invention describes the behavior of oneend of the LAG and is designed to work regardless of the behavior of theother end of the LAG. In other words, the present invention provides animproved mechanism for supporting sequence-sensitive,connection-oriented data across an aggregated link bundle whichpreserves properties of the data that are expected by an end user. Byusing a reduced number of state blocks, hardware resources are moreefficiently used. The improved mechanism of the present invention isapplicable to markets in which layer 2 technologies are being migratedto connectionless environments. For example, ATM and FRsequence-sensitive, connection-oriented circuits are being migrated toInternet Protocol/Multi-Protocol Label Switching (IP/MPLS) backbonenetworks.

In one exemplary embodiment of the present invention, a method for themanagement of sequence-sensitive, connection-oriented traffic on amulti-link aggregated port includes: at a first end of a multi-linkaggregated port, selectively enabling a first constituent link of aplurality of constituent links to transmit data traffic in a firstdirection across the first constituent link via a transmit state blockassociated with the first constituent link; and, at the first end of themulti-link aggregated port, selectively enabling the plurality ofconstituent links to receive data traffic from a second direction acrossthe plurality of constituent links via a plurality of receive stateblocks associated with the plurality of constituent links. The methodalso includes: at a second end of the multi-link aggregated port,selectively enabling a second constituent link of the plurality ofconstituent links to transmit data traffic in the second directionacross the second constituent link via a transmit state block associatedwith the second constituent link; and, at the second end of themulti-link aggregated port, selectively enabling the plurality ofconstituent links to receive data traffic from the first directionacross the plurality of constituent links via a plurality of receivestate blocks associated with the plurality of constituent links.

In another exemplary embodiment of the present invention, a system forthe management of sequence-sensitive, connection-oriented traffic on amulti-link aggregated port includes: a multi-link aggregated port havinga first end and a second end and including a plurality of constituentlinks; a transmit state block disposed at the first end of themulti-link aggregated port and associated with a first constituent linkof the plurality of constituent links, the transmit state blockassociated with the first constituent link enabling the firstconstituent link to transmit data traffic in a first direction acrossthe first constituent link; and a plurality of receive state blocksdisposed at the first end of the multi-link aggregated port andassociated with the plurality of constituent links, the plurality ofreceive state blocks associated with the plurality of constituent linksenabling the plurality of constituent links to receive data traffic froma second direction across the plurality of constituent links. The systemalso includes: a transmit state block disposed at the second end of themulti-link aggregated port and associated with a second constituent linkof the plurality of constituent links, the transmit state blockassociated with the second constituent link enabling the secondconstituent link to transmit data traffic in the second direction acrossthe second constituent link; and a plurality of receive state blocksdisposed at the second end of the multi-link aggregated port andassociated with the plurality of constituent links, the plurality ofreceive state blocks associated with the plurality of constituent linksenabling the plurality of constituent links to receive data traffic fromthe first direction across the plurality of constituent links.

In a further exemplary embodiment of the present invention, a method forthe management of sequence-sensitive, connection-oriented traffic on amulti-link aggregated port includes: selecting a first constituent linkof a plurality of constituent links to transmit data traffic in a firstdirection; selecting a second constituent link of the plurality ofconstituent links to transmit data traffic in a second direction; at afirst end of a multi-link aggregated port, selectively enabling thefirst constituent link of the plurality of constituent links to transmitdata traffic in the first direction across the first constituent linkvia a transmit state block associated with the first constituent link;at the first end of the multi-link aggregated port, selectively enablingthe plurality of constituent links to receive data traffic from thesecond direction across the plurality of constituent links via aplurality of receive state blocks associated with the plurality ofconstituent links; at a second end of the multi-link aggregated port,selectively enabling the second constituent link of the plurality ofconstituent links to transmit data traffic in the second directionacross the second constituent link via a transmit state block associatedwith the second constituent link; and, at the second end of themulti-link aggregated port, selectively enabling the plurality ofconstituent links to receive data traffic from the first directionacross the plurality of constituent links via a plurality of receivestate blocks associated with the plurality of constituent links.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated and described herein with referenceto the various drawings, in which like reference numbers denote likemethod steps and/or system components, respectively, and in which:

FIG. 1 is a schematic diagram illustrating how, using conventionalmethods and systems, data may be delivered out of order if data from thesame flow follows different constituent links associated with a LAG;

FIG. 2 is a schematic diagram illustrating how, using conventionalmethods and systems, state blocks are used by connection-orientedtraffic traversing a previously established path;

FIG. 3 is a schematic diagram illustrating a bidirectional connectionrepresented as two unidirectional connections, in accordance with themethods and systems of the present invention;

FIG. 4 is a schematic diagram illustrating one exemplary embodiment of atransmit state block/receive state block configuration, in accordancewith the methods and systems of the present invention; and

FIG. 5 is a flowchart illustrating one exemplary embodiment of aconnection setup of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

As described above, in a typical LAG environment, any of the constituentlinks of the LAG are equally able to handle data that is to betransmitted across the LAG. This is acceptable for connectionless,best-effort environments in which there is no standard relationshipbetween one packet or frame and the next packet or frame (e.g. there isno ordering relationship between one packet or frame and the next packetor frame), nor is there any need to reserve resources for said data.

Connection-oriented environments, however, use a call setup paradigm tostitch up a path from source to destination, as well as to reserveresources (such as bandwidth, queues, etc.) for a connection. Physicalresources may need to be reserved in order to provideconnection-oriented functions, such as rate enforcement and quality ofservice guarantees. In such environments, a connection defines a flowand either resources need to be allocated against all constituent linksin order to provide bandwidth and quality of service guarantees or asingle link must be chosen to handle the connection.

Sequence-sensitive, connection-oriented environments add an additionalrequirement, as data order must be preserved as data is transmittedalong a connection's path. For sequence-sensitive connections, theconstituent links of a LAG are not equally able to handle data from thesame connection, as all data for that connection must traverse the sameconstituent link in order to preserve data ordering. FIG. 1 illustrateshow, using conventional methods and systems, data may be delivered outof order if data from the same flow follows different constituent linksassociated with a LAG. Referring to FIG. 1, node 2 10 receives frame A12 and frame B 14 from node 1 16 and the LAG 18, however, node 2 10 hasno way of knowing that frame B 14 should be received, and subsequentlydelivered to node 3 20, before frame A 12. Node 2 10 simply transmitsframe A 12 and frame B 14 as they arrive. Due to scheduling, congestion,other delay, etc., frame A 12 may be processed before frame B 14,resulting in the data stream arriving at the destination in a differentorder than it was transmitted from the source (i.e. frame A 12/frame B14 at the destination, as opposed to frame B 14/frame A 12 from thesource). Thus, in order to guarantee delivery order, the sameconstituent link must be used for the transmission of data for a givenconnection or flow.

A relatively simple solution to the resource problem is to allocateresources against all links. However, this results in sub-optimalresource utilization that defeats the purpose of the LAG in the firstplace (i.e. resources allocated against a link that is not currentlybeing used to transmit data for a particular connection are wasted) anddoes not solve the data ordering problem. Another relatively simplesolution is to handle call admission control, resource allocation, andrate enforcement functions centrally for the LAG. However, this does notscale well as links are added to and removed from the LAG.

By its nature, connection-oriented traffic traverses a previouslyestablished path from source to destination. FIG. 2 illustrates how,using conventional methods and systems, state blocks are used byconnection-oriented traffic traversing a previously established path.Referring to FIG. 2, at each hop in the path along the bidirectionalconnection 30, a state block 32 is maintained for the duration of theconnection. This state block 32 contains information about theconnection, such as rate enforcement/policing state, hardware resourceallocation (hardware buffers, bandwidth, etc.), cross-connectinformation, and manipulations (adding/removing PWE3 labels, etc.). Whendata arrives on a connection, the state block 32 is referenced todetermine: a) whether to accept or drop the data (i.e. policing andhardware resource checking); b) where to forward the data (i.e. crossconnect checking); and c) how to manipulate the data (i.e. headermanipulating).

In a LAG environment, at each LAG interface, there are multipleindependent links that may be used to transmit and receive data for agiven connection. From a transmitting of sequence-sensitive trafficpoint of view, one constituent link must be selected and used for alldata in order to preserve data sequence integrity. From a receivingpoint of view, all links must be considered equally able to present datafrom a given connection. This is due to the fact that there is nocoordination between the two sides of the LAG link to agree on a givenconstituent link to use for a given connection.

The present invention provides an improved mechanism for allocatingresources and preserving the sequence of connection-oriented traffictraversing a LAG. The present invention describes the behavior of oneend of the LAG and is designed to work regardless of the behavior of theother end of the LAG.

Referring to FIG. 3, a bidirectional connection 30 (FIG. 2) may bebroken into two unidirectional connections 40,42 and handledaccordingly. During the connection setup of sequence-sensitive trafficover a LAG 18, one of the LAG's constituent links or paths 40 will bechosen to host a transmit state block 50 (FIG. 4) of the connectionbased upon predetermined criteria (bandwidth availability, etc.), whileanother of the LAG's constituent links or paths 42 will not be chosen tohost the transmit state block 50 of the connection based upon the samepredetermined criteria. Once the connection is completed, all data to betransmitted through the LAG 18 flows across the constituent link or path40 chosen during the connection setup phase. In addition, everyconstituent link in the LAG 18 must be given enough state information tohandle data received from the constituent link for the connection. Thisis called a receive state block 52 (FIG. 4), and it is created on everyconstituent link during the connection setup phase.

Referring to FIG. 4, in one exemplary embodiment of the presentinvention, a LAG 18 has three constituent links 54,56,58. Data flowingfrom left to right always flows across the third constituent link 58(where the transmit state block 50 resides in that direction). Dataflowing from right to left always flows across the second constituentlink 56 (where the transmit state block 50 resides in that direction).Both sides are able to receive data on any of the constituent links54,56,58 due to the presence of receive state blocks 52 on everyconstituent link 54,56,58. In general, resource allocation is greater onthe transmit side than on the receive side. By reducing the number oftransmit state blocks 50, resources are efficiently utilized. In thismanner, one end of a LAG 18 will use one of the constituent links 56,58for data transmission and all of the constituent links 54,56,58 for datareception, thus avoiding the need to coordinate with the other end ofthe LAG 18, while preserving data ordering.

FIG. 5 is a flowchart illustrating one exemplary embodiment of aconnection setup 60 of the present invention. The connection setup 60 isused when sequence-sensitive traffic is transmitted over a LAG. Theconnection setup 60 begins by selecting a constituent link responsive tothe transmit state block (Block 62). The transmit state block containsinformation about the connection, such as rate enforcement, policingstate, hardware resource allocation (hardware buffers, bandwidth, etc.),cross-connect information, and manipulations (adding/removing PWE3labels, etc.). The constituent link is selected based on predeterminedconditions in the transmit state block. For example, a constituent linkmay be selected because it has more bandwidth available than otherconstituent links.

The connection setup 60 enables a plurality of receive state blocksacross all constituent links (Block 64). Thus, the connection setup 60is configured to receive across any constituent link. This allows theconnection setup 60 to operate at one end, without coordinating at anopposite end, and while minimizing the number of transmit state blocks.

The connection setup 60 transmits data on the selected constituent link(Block 66). This constituent link is used throughout the transmission ofthe sequence-sensitive traffic. The connection setup 60 is performed atboth sides or ends of the connection. The constituent link selected fortransmission may be different at each side or end. This is implementedby enabling receive state blocks on all constituent links, as describedabove.

Although the present invention has been illustrated and described hereinwith reference to preferred embodiments and specific examples thereof,it will be readily apparent to those of ordinary skill in the art thatother embodiments and examples may perform similar functions and/orachieve like results. All such equivalent embodiments and examples arewithin the spirit and scope of the present invention and are intended tobe covered by the following claims.

1. A method for the management of sequence-sensitive,connection-oriented traffic on a multi-link aggregated port, the methodcomprising: at a first end of a multi-link aggregated port, selectivelyenabling a first constituent link of a plurality of constituent links totransmit data traffic in a first direction across the first constituentlink via a transmit state block associated with the first constituentlink; and at the first end of the multi-link aggregated port,selectively enabling the plurality of constituent links to receive datatraffic from a second direction across the plurality of constituentlinks via a plurality of receive state blocks associated with theplurality of constituent links.
 2. The method of claim 1, furthercomprising: at a second end of the multi-link aggregated port,selectively enabling a second constituent link of the plurality ofconstituent links to transmit data traffic in the second directionacross the second constituent link via a transmit state block associatedwith the second constituent link; and at the second end of themulti-link aggregated port, selectively enabling the plurality ofconstituent links to receive data traffic from the first directionacross the plurality of constituent links via a plurality of receivestate blocks associated with the plurality of constituent links.
 3. Themethod of claim 1, further comprising transmitting data traffic in thefirst direction across the first constituent link.
 4. The method ofclaim 2, further comprising transmitting data traffic in the seconddirection across the second constituent link.
 5. The method of claim 1,wherein the multi-link aggregated port comprises a Link AggregationGroup.
 6. The method of claim 2, wherein the transmit state blocks andreceive state blocks comprise connection information, wherein theconnection information comprises one or more of rate enforcementinformation, policing state information, hardware resource allocationinformation, bandwidth information, cross-connection information, andlabel manipulation information.
 7. The method of claim 2, furthercomprising checking a receive state block responsive to receiving datatraffic from the second direction across a constituent link in order todetermine whether to accept the data traffic, where to forward the datatraffic, and how to manipulate the data traffic.
 8. The method of claim7, further comprising updating connection information on the first endand second end of the multi-link aggregated port.
 9. A system for themanagement of sequence-sensitive, connection-oriented traffic on amulti-link aggregated port, the system comprising: a multi-linkaggregated port having a first end and a second end and comprising aplurality of constituent links; a transmit state block disposed at thefirst end of the multi-link aggregated port and associated with a firstconstituent link of the plurality of constituent links, the transmitstate block associated with the first constituent link enabling thefirst constituent link to transmit data traffic in a first directionacross the first constituent link; and a plurality of receive stateblocks disposed at the first end of the multi-link aggregated port andassociated with the plurality of constituent links, the plurality ofreceive state blocks associated with the plurality of constituent linksenabling the plurality of constituent links to receive data traffic froma second direction across the plurality of constituent links.
 10. Thesystem of claim 9, further comprising: a transmit state block disposedat the second end of the multi-link aggregated port and associated witha second constituent link of the plurality of constituent links, thetransmit state block associated with the second constituent linkenabling the second constituent link to transmit data traffic in thesecond direction across the second constituent link; and a plurality ofreceive state blocks disposed at the second end of the multi-linkaggregated port and associated with the plurality of constituent links,the plurality of receive state blocks associated with the plurality ofconstituent links enabling the plurality of constituent links to receivedata traffic from the first direction across the plurality ofconstituent links.
 11. The system of claim 9, further comprising meansfor transmitting data traffic in the first direction across the firstconstituent link.
 12. The system of claim 10, further comprising meansfor transmitting data traffic in the second direction across the secondconstituent link.
 13. The system of claim 9, wherein the multi-linkaggregated port comprises a Link Aggregation Group.
 14. The system ofclaim 10, wherein the transmit state blocks and receive state blockscomprise connection information, wherein the connection informationcomprises one or more of rate enforcement information, policing stateinformation, hardware resource allocation information, bandwidthinformation, cross-connection information, and label manipulationinformation.
 15. The system of claim 10, further comprising means forchecking a receive state block responsive to receiving data traffic fromthe second direction across a constituent link in order to determinewhether to accept the data traffic, where to forward the data traffic,and how to manipulate the data traffic.
 16. The system of claim 15,further comprising means for updating connection information on thefirst end and second end of the multi-link aggregated port.
 17. A methodfor the management of sequence-sensitive, connection-oriented traffic ona multi-link aggregated port, the method comprising: selecting a firstconstituent link of a plurality of constituent links to transmit datatraffic in a first direction; selecting a second constituent link of theplurality of constituent links to transmit data traffic in a seconddirection; at a first end of a multi-link aggregated port, selectivelyenabling the first constituent link of the plurality of constituentlinks to transmit data traffic in the first direction across the firstconstituent link via a transmit state block associated with the firstconstituent link; at the first end of the multi-link aggregated port,selectively enabling the plurality of constituent links to receive datatraffic from the second direction across the plurality of constituentlinks via a plurality of receive state blocks associated with theplurality of constituent links; at a second end of the multi-linkaggregated port, selectively enabling the second constituent link of theplurality of constituent links to transmit data traffic in the seconddirection across the second constituent link via a transmit state blockassociated with the second constituent link; and at the second end ofthe multi-link aggregated port, selectively enabling the plurality ofconstituent links to receive data traffic from the first directionacross the plurality of constituent links via a plurality of receivestate blocks associated with the plurality of constituent links.
 18. Themethod of claim 17, further comprising transmitting data traffic in thefirst direction across the first constituent link.
 19. The method ofclaim 17, further comprising transmitting data traffic in the seconddirection across the second constituent link.
 20. The method of claim17, wherein the multi-link aggregated port comprises a Link AggregationGroup.
 21. The method of claim 17, wherein the transmit state blocks andreceive state blocks comprise connection information, wherein theconnection information comprises one or more of rate enforcementinformation, policing state information, hardware resource allocationinformation, bandwidth information, cross-connection information, andlabel manipulation information.
 22. The method of claim 17, furthercomprising checking a receive state block responsive to receiving datatraffic from the second direction across a constituent link in order todetermine whether to accept the data traffic, where to forward the datatraffic, and how to manipulate the data traffic.
 23. The method of claim22, further comprising updating connection information on the first endand second end of the multi-link aggregated port.